I was talking with my buddy Ken Casey, who is the parts manager at John Elway Chevrolet in Englewood, Colorado. We started talking about the Chevrolet Performance LS3 and how he felt that this engine was perhaps the overlooked jewel in the 2015 catalog. The engine was introduced several years ago as a 430 hp crate engine that was the engine in the Corvette from 2008 to 2013. While the horsepower rating isn’t that impressive in the days of 600 hp supercharged engines, this may be why the engine has been shuffled aside in the press as they focus on bigger horsepower numbers.

I too am guilty of the oversight. My approach has always been to buy a used motor out of the junkyard or from Craigslist and then rebuild it to my personal taste. The plan has been to do the work myself and save the money that would otherwise go to paying someone else. But looking back, this has not always worked out in my favor. I’ve been duped into buying a small-block boat anchor that suffered from scorched main bearings and I’ve also been the victim of purchasing a 4.8L truck engine believing it to be 5.3L. All of these engines have been iron block engines because they’re cheap.

About six years ago, I built a stroker 404ci LS engine that started out as a 6.0L motor. This was when the LS population was thinner and not nearly as affordable as it is today. I bought that iron 6.0L and put a Scat stroker package in with Mahle pistons and a COMP Cam and topped it with a set of the old CNC-ported L92 Chevrolet Performance cylinder heads. This engine was intended for a supercharger so it only had 9.8:1 compression. It took a month of time to get the machine work done and then another few evenings assembling this rascal. It took a little longer because this was my first LS engine build, but it was fun and I learned a ton about the LS engine family.

The opposite side of this was the disappointment that followed when I added up all that it took to assemble the engine. My story in Car Craft in the January 2010 issue listed the entire cost at over $8,000. Granted, that included everything you would need including a carbureted intake manifold and Holley carb, the MSD ignition, new balancer, oil filter and all the stuff that it takes to assemble a running engine. It was also a bit of a letdown that it only made 560 hp. Since then, a new lineup of cams would probably push that number up to something closer to 575 hp or perhaps even higher.

After my talk with Ken Casey, I started to compare both prices and power numbers for Chevrolet Performance’s upgraded LS3 versions. The first upgrade is the same LS3 with a stronger HOT cam (219/228 with 0.525-inch lift) that pushes the horsepower to 480 and the torque jumps from 424 to 475 at 4,500 rpm. Then there’s a long block engine called the LS376/515 (PN 19301359) that employs an ASA circle track camshaft, better valve springs, and a single plane carbureted intake that combine to make 515 hp and 469 lb-ft of torque. The ASA cam bumps the duration to 226/236 degrees at 0.050 with 0.525-inch valve lift numbers for both.

The final upgraded version of the LS3 is the 376/525 package that adds the ASA circle track camshaft and valve springs but retains the LS3 intake manifold (PN 19301360). This package makes another 10 hp at peak and also 20 lb-ft more torque (489 lb-ft at 4,400) compared to the carbureted version. While this engine is packaged as a circle track crate engine, it seems to me that it would make an outstanding street engine. I started investigating and it appears that it might actually be less expensive to buy the base crate LS3 and then add your own camshaft as there are at least a dozen variations that would make similar if not more power.

I priced the base engine at roughly $6,700 through several different suppliers, which with the addition of the ASA cam would push this smaller 376ci engine to 525 horsepower which is only about 35 hp shy of my effort with a larger 404ci engine. To make the comparison even more fair, if we add just 1 hp per cubic inch to make the LS3 the same displacement as my 404 motor, this puts the power almost equal to my home built engine.

If you retain the EFI, you will need some kind of EFI controller like the factory system or one from BigStuff3, FAST, Holley, MSD, or one of the other systems to run this package. The GM system is really affordable and even comes with an electronic throttle pedal which would negate the need for a mechanical throttle body. Add some type of accessory drive like the non-A/C kit from GM (PN 19257325) that includes a new alternator and power steering pump and you’ve got the makings of an excellent street engine making 525 hp that’s fully EFI controlled that will run almost like a new car. That’s pretty cool.

In a 3,500 pound street car with decent traction, the stock LS3 425 hp engine has the potential to run low 12’s at 109 mph. This kind of performance is available for probably under $8,500 complete and bolted in your chassis ready to race. Even better, any of the engines I’ve mentioned come with 24-month, 80,000 mile warranty. I’m looking at this in a whole new light now. And why not?